It is generally desirable to operate a granular material conveyor as close to its maximum capacity as possible in order to reduce the time needed to make a transfer. For example in agricultural operations granular material conveyors, typically auger or belt conveyors, are commonly used to transfer agricultural products. At seeding time agricultural products are moved by conveyors from storage facilities to a transport vehicle and then from the transport vehicle to a seeding implement. Similarly at harvest time harvested crops such as grains, beans, etc. are moved by conveyors from harvesting equipment to transport vehicles, and from the transport vehicles to storage facilities.
Such agricultural operations are quite time sensitive since the time suitable for seeding and harvesting is limited by weather conditions. Generally speaking time spent loading and unloading transport vehicles with a conveyor is considered unproductive down time so it can be said that operating a granular material conveyor as near to capacity as possible is desirable to reduce this down time.
A typical conveyor used in the agricultural industry is disclosed for example in U.S. Pat. Nos. 8,118,151 and 8,365,896 to Jesse. The conveyor comprises a tube mounted on a frame and wheels for movement and for raising and lowering the discharge end of the conveyor. A belt or auger runs inside the tube. Conventional dump trucks for transporting agricultural products have a box mounted on the truck frame and a hoist operative to pivot the front end of the box upward about a horizontal pivot axis at the rear of the truck frame so the products in the box flow out through a discharge opening in the lower rear wall of the box, with the rate of product flow into the conveyor intake controlled by a gate that adjusts the size of the discharge opening. The truck is backed up to the lower intake end of the conveyor to align the discharge opening with the conveyor intake, and the hoist is raised.
Agricultural products are also often transported in hoppered trailers where the discharge opening is in the middle of the bottom of the trailer. Conveyors such as disclosed by of Jesse cannot be positioned to receive the product from such a belly dump discharge opening and so swing augers have been developed such as disclosed in U.S. Pat. No. 7,191,889 to Heley. Heley shows an auger conveyor but a similar configuration is known and used where the conveyor is a belt conveyor. The conveyor of Heley includes a main conveyor with a short swing conveyor pivotally attached at the discharge end thereof to the intake of the main conveyor. Once the trailer is in position the intake hopper on the outer end of the swing auger is moved under the discharge opening to receive the product, and a gate again is operated to control flow of product into the conveyor intake. A typical intake hopper has upward and outward sloping walls to receive the product and direct same to a conveyor auger or belt at the bottom of the walls.
U.S. Pat. No. 7,946,416 to Grose et al. discloses a swing auger where the swing auger moves in and out with respect to the intake of the main conveyor so the hopper of the swing auger can be moved close to the main conveyor intake to allow the trailer to drive into position, then the hopper can be moved away from the main intake under the discharge openings in the middle of the bottom of hoppered trailers.
U.S. Pat. No. 8,992,156 to Haukaas, et al. discloses a transfer conveyor mounted to a hoppered trailer to receive granular material from the center discharge opening and transfer same to a main conveyor intake beside the trailer. U.S. Pat. No. 7,063,497 to Mast et al. and United States Published Patent Application Number 20040136817 of Kirsch disclose a conveyor where the trailer is driven over the intake portion of the swing auger to align the trailer's discharge opening with the conveyor intake.
Once the discharge opening on the truck or trailer is aligned with the conveyor intake the gates on the discharge openings are operated manually with a crank or lever, or remotely where an actuator is present to move the gate to control the rate flow into the conveyor intake. In a typical operation the operator will visually monitor the conveyor intake and move the gate open or closed to ensure the rate of material flow is not greater than the rate of material transfer by the conveyor, such that the material builds up and overflows the hopper, but also so the rate of material flow is not significantly less than the rate of material transfer by the conveyor, thereby increasing the time that is required to empty the truck or trailer.
United States Published Patent Application Number 2014/0343723 of Meier et al. discloses a bin spill prevention system has a sensor on the discharge of a conveyor to sense when a storage bin is full and then closes a truck discharge gate that is directing material into the conveyor.